1 /* 2 * This file is included twice from vdso2c.c. It generates code for 32-bit 3 * and 64-bit vDSOs. We need both for 64-bit builds, since 32-bit vDSOs 4 * are built for 32-bit userspace. 5 */ 6 7 static void BITSFUNC(go)(void *raw_addr, size_t raw_len, 8 void *stripped_addr, size_t stripped_len, 9 FILE *outfile, const char *name) 10 { 11 int found_load = 0; 12 unsigned long load_size = -1; /* Work around bogus warning */ 13 unsigned long mapping_size; 14 ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr; 15 int i; 16 unsigned long j; 17 ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr, 18 *alt_sec = NULL; 19 ELF(Dyn) *dyn = 0, *dyn_end = 0; 20 const char *secstrings; 21 INT_BITS syms[NSYMS] = {}; 22 23 ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_LE(&hdr->e_phoff)); 24 25 /* Walk the segment table. */ 26 for (i = 0; i < GET_LE(&hdr->e_phnum); i++) { 27 if (GET_LE(&pt[i].p_type) == PT_LOAD) { 28 if (found_load) 29 fail("multiple PT_LOAD segs\n"); 30 31 if (GET_LE(&pt[i].p_offset) != 0 || 32 GET_LE(&pt[i].p_vaddr) != 0) 33 fail("PT_LOAD in wrong place\n"); 34 35 if (GET_LE(&pt[i].p_memsz) != GET_LE(&pt[i].p_filesz)) 36 fail("cannot handle memsz != filesz\n"); 37 38 load_size = GET_LE(&pt[i].p_memsz); 39 found_load = 1; 40 } else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) { 41 dyn = raw_addr + GET_LE(&pt[i].p_offset); 42 dyn_end = raw_addr + GET_LE(&pt[i].p_offset) + 43 GET_LE(&pt[i].p_memsz); 44 } 45 } 46 if (!found_load) 47 fail("no PT_LOAD seg\n"); 48 49 if (stripped_len < load_size) 50 fail("stripped input is too short\n"); 51 52 /* Walk the dynamic table */ 53 for (i = 0; dyn + i < dyn_end && 54 GET_LE(&dyn[i].d_tag) != DT_NULL; i++) { 55 typeof(dyn[i].d_tag) tag = GET_LE(&dyn[i].d_tag); 56 if (tag == DT_REL || tag == DT_RELSZ || tag == DT_RELA || 57 tag == DT_RELENT || tag == DT_TEXTREL) 58 fail("vdso image contains dynamic relocations\n"); 59 } 60 61 /* Walk the section table */ 62 secstrings_hdr = raw_addr + GET_LE(&hdr->e_shoff) + 63 GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx); 64 secstrings = raw_addr + GET_LE(&secstrings_hdr->sh_offset); 65 for (i = 0; i < GET_LE(&hdr->e_shnum); i++) { 66 ELF(Shdr) *sh = raw_addr + GET_LE(&hdr->e_shoff) + 67 GET_LE(&hdr->e_shentsize) * i; 68 if (GET_LE(&sh->sh_type) == SHT_SYMTAB) 69 symtab_hdr = sh; 70 71 if (!strcmp(secstrings + GET_LE(&sh->sh_name), 72 ".altinstructions")) 73 alt_sec = sh; 74 } 75 76 if (!symtab_hdr) 77 fail("no symbol table\n"); 78 79 strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) + 80 GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link); 81 82 /* Walk the symbol table */ 83 for (i = 0; 84 i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize); 85 i++) { 86 int k; 87 ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) + 88 GET_LE(&symtab_hdr->sh_entsize) * i; 89 const char *name = raw_addr + GET_LE(&strtab_hdr->sh_offset) + 90 GET_LE(&sym->st_name); 91 92 for (k = 0; k < NSYMS; k++) { 93 if (!strcmp(name, required_syms[k].name)) { 94 if (syms[k]) { 95 fail("duplicate symbol %s\n", 96 required_syms[k].name); 97 } 98 99 /* 100 * Careful: we use negative addresses, but 101 * st_value is unsigned, so we rely 102 * on syms[k] being a signed type of the 103 * correct width. 104 */ 105 syms[k] = GET_LE(&sym->st_value); 106 } 107 } 108 } 109 110 /* Validate mapping addresses. */ 111 for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) { 112 INT_BITS symval = syms[special_pages[i]]; 113 114 if (!symval) 115 continue; /* The mapping isn't used; ignore it. */ 116 117 if (symval % 4096) 118 fail("%s must be a multiple of 4096\n", 119 required_syms[i].name); 120 if (symval + 4096 < syms[sym_vvar_start]) 121 fail("%s underruns vvar_start\n", 122 required_syms[i].name); 123 if (symval + 4096 > 0) 124 fail("%s is on the wrong side of the vdso text\n", 125 required_syms[i].name); 126 } 127 if (syms[sym_vvar_start] % 4096) 128 fail("vvar_begin must be a multiple of 4096\n"); 129 130 if (!name) { 131 fwrite(stripped_addr, stripped_len, 1, outfile); 132 return; 133 } 134 135 mapping_size = (stripped_len + 4095) / 4096 * 4096; 136 137 fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n"); 138 fprintf(outfile, "#include <linux/linkage.h>\n"); 139 fprintf(outfile, "#include <asm/page_types.h>\n"); 140 fprintf(outfile, "#include <asm/vdso.h>\n"); 141 fprintf(outfile, "\n"); 142 fprintf(outfile, 143 "static unsigned char raw_data[%lu] __ro_after_init __aligned(PAGE_SIZE) = {", 144 mapping_size); 145 for (j = 0; j < stripped_len; j++) { 146 if (j % 10 == 0) 147 fprintf(outfile, "\n\t"); 148 fprintf(outfile, "0x%02X, ", 149 (int)((unsigned char *)stripped_addr)[j]); 150 } 151 fprintf(outfile, "\n};\n\n"); 152 153 fprintf(outfile, "const struct vdso_image %s = {\n", name); 154 fprintf(outfile, "\t.data = raw_data,\n"); 155 fprintf(outfile, "\t.size = %lu,\n", mapping_size); 156 if (alt_sec) { 157 fprintf(outfile, "\t.alt = %lu,\n", 158 (unsigned long)GET_LE(&alt_sec->sh_offset)); 159 fprintf(outfile, "\t.alt_len = %lu,\n", 160 (unsigned long)GET_LE(&alt_sec->sh_size)); 161 } 162 for (i = 0; i < NSYMS; i++) { 163 if (required_syms[i].export && syms[i]) 164 fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n", 165 required_syms[i].name, (int64_t)syms[i]); 166 } 167 fprintf(outfile, "};\n"); 168 } 169